This invention relates generally to canter chipper heads and more particularly to precision and secure mounting of the cutters and to refinements to the shape of the head.
Chipper canters are know as are also canter heads with cutting knives removably mounted thereon and by way of example reference may be had to applicants U.S. Pat. No. 5,915,429 ISSUED Jun. 29, 1999 and entitled xe2x80x9cCOMPACT SMALL DIAMETER LOG SAWMILLxe2x80x9d.
Disclosed in applicants above patent (FIGS. 12-23) is a chipper canter head having chip discharge openings through a truncated conical portion of the head and a pair of cutting knives mounted adjacent each opening. The cutting edge of one knife extends along an edge of the opening in the conical portion of the head and the other knife cutting edge extends along an edge of the opening in an outer relatively flat end face of the head. The blades are removably mounted by studs passing through the respective blades and threaded into the head or by bolt and nut units.
Blades must be kept sharp and to do this they must be removed from the head. This can occur as often as each daily shift of operation and thus it is necessary the mounting means be readily accessible. In some prior art arrangements the mount securement is a bolt and nut with the nut accessible only from the rear face of the head. In such cases it is often necessary to remove the head from the canter drive shaft before attempting to remove the cutting blade.
The quality of the chips and the cant face is determined by not only by the sharpness of the cutting knives but also the precision of the head, the precision in positioning of the knives on the head and the rigidity of the head and blades thereon.
In an attempt to obtain some degree of precision in locating the cutting knives some are adjustably positionable and in this regard reference may be had to the following United States Patents:
U.S. Pat. No. 5,709,255 issued Jan. 20, 1998 to W. Toogood
U.S. Pat. No. 5,511,597 issued Apr. 30, 1996 to M. Shantie et al
U.S. Pat. No. 5,439,039 issued Aug. 8, 1995 to J. Bradstreet Jr et al
U.S. Pat. No. 5,2271,442 issued Dec. 21, 1993 to C. Carpenter
These references also disclose a knife unit in which a double edge replaceable blade is clamped between a backing plate and a cover plate. This permits having only the blade made of high quality material such as tool steel or the like. The knife unit is removably mounted on a holder that bolts onto a hub.
While the knife unit is an improvement positioning can change from impact forces on the blades during use because of the many assembled components.
An object of the present invention is to provide a rugged precision mounting of cutting blades on a chipper canter head.
A further principal object of the present invention is to provide a knife mounting means that is readily accessible from the front face of the canter head.
A still further object of the present invention is to provide refinements to the shape of the one piece canter head.
In keeping with the forgoing there is provided in accordance with the present invention a chipper canter head comprising a base member machine shaped from a monolithic block of metal and having a truncated conical outer front face terminating in an outer end face, a rear face, at least two spaced apart chip discharge passages through said truncated conical portion and each having a continuous outline in each of said front and rear faces, each said passage extending into said outer end face, a pair of cutter units for each respective passage, each said cutter unit comprising a bottom plate, a top plate and a knife blade, said knife blade being clampingly engagable between said plates and having a longitudinally extending cutting edge projecting therefrom and means detachably mounting said cutter units on said canter head with the knife cutting edges disposed adjacent and along an edge of the opening to the discharge passage associated therewith, said mounting means comprising a first bolt means passing through said bottom plate detachably anchoring the same to said base member and a second bolt means passing through said top plate and said bottom plate anchoring the top plate to the base member and clampingly engaging the knife blade between said plates.